Arsenopyrite, Gold & Pyrite

Gold is a valuable, highly prized mineral used in everything from jewellery to electronics and dentistry. Gold is desirable due to its special properties, such as malleability and resistance to tarnishing. Gold is commonly microscopic or embedded within or around sulphide grains. Free visible gold occurs as disseminated grains, or rarely as crystals. In its natural mineral form, gold is commonly alloyed with silver. Gold is distinguishable by its characteristic golden yellow colour and extreme heaviness.

Pyrite is a common iron sulphide mineral found in many different geological settings. It has a brassy-yellow metallic colour that has caused many people to mistake it for gold, giving it the name “Fool’s gold”. Pyrite and gold can be quite easily distinguished from one another: pyrite is less yellow and much lighter and harder than gold, which can be scratched with a pocket knife. Pyrite often forms perfect cubes, which can grow to quite large sizes, because of its crystal structure. The word pyrite comes from the Greek word ‘pyr’ meaning fire, because it will spark if hit with other metal or stone objects.

Arsenopyrite is a sulphide similar to pyrite but contains arsenic as well as iron. It has a more silvery colour than pyrite and forms blocky or tabular crystals rather than cubes. Its surface often has striations, or stripes. Arsenopyrite is one of the main ore minerals for arsenic, which is used in wood preservatives and insecticides. In its oxide forms, arsenic is toxic so it is not widely used.

This sample is from the Cousin Jack property near Tulameen, about 25 km northwest of Princeton in southern BC.

Mineralization at Cousin Jack is in quartz-carbonate veins that contain varying amounts of pyrite, arsenopyrite, sphalerite, galena, gold and silver. This sample contains pale arsenopyrite, yellow pyrite and small amounts of gold.

The area has been prospected and staked since the early 1900s, and even explored with short test adits, but so far no major deposits have been found or mined on the Cousin Jack properties.

Specimen Information

Store: Association for Mineral Exploration (AME)

Collection: –

Accession #: AME 161

Primary Mineral: Arsenopyrite, Gold & Pyrite

Secondary Mineral: –

Site Locality: Cousin Jack

Location: Tulameen, British Columbia

Special Features: n/a

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